I don't think any card or deck can ever be labeled invincible; there's just too many variables there. Who's playing it, what cards are prized, what the opening hand was, card placement, mistakes, etc.
However, it is a very good deck. I've played it many a time, and lost to it most of those times. There are still plenty of ways to beat it, though. Specifically, I've seen Machamp and AMU do fantastic against it.